Field of the Invention
The present invention relates to a light control device and a transparent display device.
Discussion of the Related Art
Recently, as society advances to the information-oriented society, the display field of processing and displaying a massive amount of information is rapidly advancing, and correspondingly, various flat panel display (FPD) devices have been developed and are attracting much attention. Examples of the FPD devices include liquid crystal display (LCD) devices, plasma display panel (PDP) devices, field emission display (FED) devices, electroluminescence display (ELD) devices, organic light emitting diode (OLED) display devices, etc.
Recently, display devices are becoming miniaturized, light, and lowered in consumption power, and thus, the application fields of the display devices are continuously increasing. Particularly, in most electronic devices or mobile devices, a display device is used as a type of user interface.
Moreover, transparent display devices which enable a user to look at a background or an object located behind the transparent display devices are being actively researched recently. The transparent display devices are good in space availability, interior, and design and may be applied to various fields. The transparent display devices realize an information recognition function, an information processing function, and an information display function by using a transparent electronic device, thereby solving the spatial limitation and visual limitation of electronic devices. For example, a transparent display device may be applied to windows of buildings or vehicles and thus may be implemented as a smart window which allows a background to be seen or displays an image.
A transparent display device may be implemented as an organic light emitting display device. In this case, power consumption is small, but a contrast ratio is not changed in a dark environment and is reduced in an environment having light. A contrast ratio based on the dark environment may be defined as a dark room contrast ratio, and a contrast ratio based on the environment having light may be defined as a bright room contrast ratio. That is, the transparent display device includes a transmissive area in order for a user to look at a background or an object located behind the transparent display device, and for this reason, the bright room contrast ratio is reduced. Therefore, in a case where the transparent display device is implemented as an organic light emitting display device, a light control device that realizes a light shield mode for blocking light and a transmissive mode for transmitting light is needed for preventing the bright room contrast ratio from being reduced.
FIG. 1 is a diagram schematically illustrating a bonding process for a light control device according to a related art. FIG. 2 is a diagram illustrating a problem of the bonding process according to the related art.
As illustrated in FIGS. 1 and 2, the light control device includes an upper film substrate and a lower film substrate, and the upper film substrate is bonded to the lower film substrate through a lamination process. In this case, since there is no boundary between a sealant and a liquid crystal layer, the sealant spreads to an active area of the liquid crystal layer. That is, sealants in a start area A and an end area B are non-uniformly distributed depending on a lamination process direction.
The non-uniform spread of the sealants affects a process of designing a cell gap of each of the upper film substrate and the lower film substrate and a process of designing a bezel, where an image is not displayed, in a display device equipped with the light control device.
Moreover, in the display device equipped with the light control device according to the related art, when the sealants spread to the active area where an image is displayed, the spread of the sealants becomes a direct cause of a display defect.